Aluminum alloys for display frames

ABSTRACT

Described is a method for forming an internal frame configured to receive a flat screen display. Aggressive partial annealing is applied to a hard temper 5182 aluminum alloy material having magnesium content greater than or equal to 3.0 wt. %. The material is partial annealed to an extent that the hard temper aluminum alloy is substantially softened with respect to its initial hardened temper while not exceeding the point where recrystallization occurs. An internal frame for a flat screen display is formed from the partial annealed aluminum alloy.

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/411,242 filed Apr. 26, 2006, the entire disclosure of whichis incorporated herein by reference. This application includes materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patentdisclosure, as it appears in the Patent and Trademark Office files orrecords, but otherwise reserves all copyright rights whatsoever.

FIELD OF THE INVENTION

The present invention relates in general to the field of frames forcomputer and video display screens, and in particular to novel displayscreen frames comprising particular aluminum alloys and/or tempers.

BACKGROUND OF THE INVENTION

Flat screen video displays, such as LCD monitors, plasma televisions,and the like, have internal frames which provide a structural supportfor components of the display. Such frames further provide a degree ofprotection for components of the display such as the relatively fragiledisplay panel, e.g., an LCD panel. These frames are typically formedfrom stainless steel. While stainless steel provides an acceptablecombination of formability and strength, stainless steel is relativelyexpensive and heavy (high density).

Aluminum alloys have been suggested for use in LCD monitor frames.Several readily available aluminum alloys have seemingly appropriateproperties for such applications. These alloys include, e.g., 6xxx(particularly 6061-T4 and -T6), 5182, and 5052 alloys. However, suchaluminum alloys do not provide an adequate solution. In particular, someof these materials crack during forming due to insufficent formability.Others distort, due to inadequate strength, in a drop test.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an improved videodisplay frame which overcomes one or more limitations of the prior art.

It is a further object of the invention to provide an LCD display framewhich is less costly to manufacture.

It is a further object of the invention to provide an LCD display framewhich performs comparably to that of stainless steel, but which providesadvantages in terms of cost, availability, reduced weight, and/ormechanical or electrical properties.

In one embodiment, the invention provides a method for forming aninternal frame configured to receive a flat screen display. Aggressivepartial annealing is applied to a hard temper 5182 aluminum alloymaterial having magnesium content greater than or equal to 3.0 wt. %.The material is partial annealed to an extent that the hard temperaluminum alloy is substantially softened with respect to its initialhardened temper while not exceeding the point where recrystallizationoccurs. An internal frame for a flat screen display is formed from thepartial annealed aluminum alloy.

In an alternative embodiment, a sheet of 5182 aluminum alloy material isannealed to a fully soft O-temper condition. The sheet is then coldrolled to achieve thickness reduction in the range 20 to 30%. Aninternal frame for a flat screen display is formed from the annealed andcold rolled sheet material.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments as illustrated in the accompanyingdrawings, in which reference characters refer to the same partsthroughout the various views. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating principles of theinvention.

FIG. 1 is a graphical illustration of elongation values vs. TYS (MPa)for 1xxx, 3xxx, and 5xxx alloys.

FIG. 2 shows a chart illustrating change in TYS and elongation of a hardtemper of 0.23 mm 5182 alloy annealed at 246° C. (475° F.).

FIG. 3 shows a perspective view illustrating a display including analuminum alloy frame in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In an embodiment of the invention, a display frame is formed from a 5182aluminum alloy as defined in the Aluminum Association's AluminumStandards and Data book. Series 6xxx alloys are very difficult toproduce in thin sheets due to distortion during quenching. Varioustempers of 5052 (for example, H32) do not have adequate strength toresist distortion during drop testing. Hardened tempers of 5182 (forexample, H39) do not have sufficient formability to endure the rigors offorming the parts.

However, aggressive partial annealing of hard tempers (e.g., H18 or H19)of high magnesium 5182 alloys provides a material that has a desirablecombination of formability and strength for internal LCD monitor frames.Recrystallization should not be allowed to occur during the partialannealing treatment, otherwise the strength would become too low for theapplication. The extent of the partial annealing treatment should besufficient to substantially soften the material from the initialhardened temper, while not causing recrystallization to occur. Thesoftened temper imparts good formability to the sheet, and the highmagnesium content imparts improved strength through rapid work hardeningduring forming of the part, and possibly also due to the distortionoccurring during drop testing of the finished assembly.

FIG. 1 shows elongation values vs. tensile yield strength (MPa) for1xxx, 3xxx, and 5xxx alloys in the Aluminum Standards and Data Book forwhich elongation values for 1.6mm thick specimens were given. It isobserved that only alloys and tempers containing ≧3.0 wt. % magnesiumgenerally can obtain attractive combinations of high yield strength(>200 MPa) and high ductility (elongation >10%). Even within the smallgroup of high Mg alloys highlighted within the box in the plot of FIG.1, the compromise between elongation and yield strength can be seen. Anexample of a hard temper of 5182 that had been aggressively partialannealed in accordance with this invention is also shown within the box.The TYS-elongation combination of this particular 5182 sample does notappear particularly impressive relative to many of the high Mg alloyswithin the box, but it should be noted that the measurement ofelongation increases with sample thickness, and the 5182 in this casewas at 0.23 mm compared to 1.59 mm for all the other samples.

Another potential method for achieving a desirable combination of TYSand elongation in 5182 is to anneal a sheet of 5182 aluminum alloymaterial to the fully soft O-temper condition and then cold roll thesheet to achieve thickness reduction in the range 20 to 30%. As anexample, 5182 cold rolled to 26% thickness reduction has been found toachieve yield strength and elongation, when tested in the longitudinaldirection, of 282 MPa (41.0 ksi) and 10.5%, respectively. A furtherpossibility is to use a slightly hardened temper as the startingmaterial, e.g. HX2, and cold roll that sheet a small amount in order toachieve an attractive combination of TYS and elongation.

An aggressive partial anneal of a hard temper of 5182 has been found toprovide a very attractive combination of strength (TYS) and ductility(elongation) suitable for the production of items such as the internalframes for LCD displays.

Tensile tests were conducted on sheet samples of 0.23 mm thick hardtemper 5182 aluminum alloy material before and after annealing forvarious times at 246° C. (475° F.). The non-annealed material had highTYS, but elongation was inadequate (<8%) for forming LCD monitor frames.FIG. 2 shows change in TYS and elongation of a hard temper of 0.23 mm5182 alloy annealed at 246° C. (475° F.).

As can be seen from FIG. 2, after annealing for 0.5 or 1.0 hours,elongation improves to >12% and TYS is still very attractive (>250 MPa).Microstructural examination revealed that recrystallization was justbeginning in the sample annealed for 1 hour. After annealing for 2hours, the sample was observed to have about 3% recrystallization.Elongation had improved to over 13%, but TYS already had dropped to alevel considered unattractive (>250 MPa). It was clear, therefore, thatto retain attractive levels of TYS, recrystallization in even very lowquantities could not be tolerated.

FIG. 3 shows a display including an aluminum alloy frame in accordancewith an embodiment of the invention. An interior frame 301 receives andsupports a display panel 303. The framed display panel 303, in turn, isreceived by an outer frame 305. As will be apparent to those of skill inthe art, the display panel 303 may be any flat screen display type,including, e.g., LCD, TFT, plasma, DLP, or the like.

The material described herein may be manufactured using a conventionalrolling mill or via the well-known micro mill process. The micro millprocess is described in U.S. Pat. Nos. 5,470,405, 5,514,228, 5,356,495,5,363,902, 5,515,908, 5,564,491, 5,496,423, 5,655,593, 5,894,879,5,772,799, 5,772,802, 6,045,632, 5,862,582, 5,742,993, 5,769,972,6,102,102, 6,391,127, 6,063,215, 6,044,896, 6,623,797, 6,082,659,D-433,206, 6,135,199, 6,672,368 and 7,182,825, which are incorporatedherein by reference.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method for forming an internal frame configured to receive a flatscreen display, comprising: aggressively partial annealing a hard temper5182 aluminum alloy material having magnesium content greater than orequal to 3.0 wt. %, said aluminum alloy material having an initialhardened temper prior to said step of aggressively partial annealing,said step of aggressively partial annealing comprising partial annealingto an extent that said hard temper aluminum alloy is substantiallysoftened with respect to said initial hardened temper while notexceeding the point where recrystallization occurs; and, forming aninternal frame for a flat screen display from said partial annealedaluminum alloy.
 2. The method for forming an internal frame configuredto receive a flat screen display according to claim 1, wherein said hardtemper 5182 aluminum alloy comprises an aluminum alloy with an H18temper.
 3. The method for forming an internal frame configured toreceive a flat screen display according to claim 1, wherein said hardtemper 5182 aluminum alloy comprises an aluminum alloy with an H19temper.
 4. The method for forming an internal frame configured toreceive a flat screen display according to claim 1, wherein said hardtemper 5182 aluminum alloy comprises an aluminum alloy with an H2Xtemper.
 5. The method for forming an internal frame configured toreceive a flat screen display according to claim 1, wherein said hardtemper 5182 aluminum alloy comprises an aluminum alloy with a temper atleast as hard as H18.
 6. The method for forming an internal frameconfigured to receive a flat screen display according to claim 1,wherein said step of aggressively partial annealing results in an alloyhaving a yield strength greater than 200 MPa and elongation greater than10%.
 7. The method for forming an internal frame configured to receive aflat screen display according to claim 1, further comprising: formingsaid partial annealed aluminum alloy into a sheet prior to forming saidinternal frame.
 8. A method for forming a flat screen display,comprising: forming an internal frame for a flat screen display from ahard temper 5182 aluminum alloy material having magnesium contentgreater than or equal to 3.0 wt. %, said 5182 aluminum alloy having beenaggressively partial annealed from an initial hardened temper such thatthe material is substantially softened while not exceeding the pointwhere recrystallization occurs; inserting a display panel into saidinternal frame; inserting said internal frame into an external frame. 9.The method for forming a flat screen display according to claim 1,wherein said hard temper 5182 aluminum alloy comprises an aluminum alloywith an H18 temper.
 10. The method for forming a flat screen displayaccording to claim 1, wherein said hard temper 5182 aluminum alloycomprises an aluminum alloy with an H19 temper.
 11. The method forforming a flat screen display according to claim 1, wherein said hardtemper 5182 aluminum alloy comprises an aluminum alloy with an H2xtemper.
 12. The method for forming a flat screen display according toclaim 1, wherein said hard temper 5182 aluminum alloy comprises analuminum alloy with a temper at least as hard as H18.
 13. The method forforming an internal frame configured to receive a flat screen displayaccording to claim 1, wherein said step of aggressively partialannealing results in an alloy having a yield strength greater than 200MPa and elongation greater than 10%.
 14. A method for forming aninternal frame configured to receive a flat screen display, comprising:annealing a sheet of 5182 aluminum alloy material to a fully softO-temper condition; cold rolling the sheet to achieve thicknessreduction in the range 20 to 30%; and, forming an internal frame for aflat screen display from said annealed and cold rolled sheet material.15. The method in accordance with claim 14, wherein said cold rollingstep comprises cold rolling the sheet to achieve thickness reduction of26%.